map --映射
let arr=[66,59,80];
let result=arr.map(item => {
if(item >= 60){
return "及格"
}else{
return "不及格"
}
});
//result:["及格", "不及格", "及格"]
reduce --汇总
let arr = [12,69,180,8763];
let result = arr.reduce((tmp, item, index) => {
console.log(tmp, item, index);
return tmp + item;
});
console.log(result);//求和
filter --过滤
let arr=[
{title: '电源线', price: 50},
{title: '电脑', price: 13000},
{title: '键盘', price: 120},
{title: '手机', price: 9000}
];
let result=arr.filter(json=>json.price>=5000);
console.log(result);//[{title: '电脑', price: 13000},{title: '手机', price: 9000}]
forEach --迭代
let arr=[12,5,8,9];
arr.forEach((item,index)=>{
console.log(index+': '+item); //0: 12 1: 5 2: 8 3: 9
});